Conventional portable audio systems often include a headphone that is connected to a media player (e.g., by one or more wires or by wireless technology). Conventional headphones may include one or two speaker assemblies having an audio driver that produces audible sound waves with a diaphragm. For example, FIGS. 1 and 2 illustrate speaker assemblies 100 and 200, respectively, for a conventional headphone.
Referring to FIG. 1, the speaker assembly 100 may include a diaphragm 110 connected to a rim of a support structure 120. The diaphragm 110 may be a disk-shaped element configured to vibrate when a magnet or electromagnetic coil attached to the diaphragm 110 moves back and forth in a magnetic field responsive to an audio signal. As a result, the diaphragm 110 generates audible sound waves in the air proximate the speaker assembly 100 that correspond to the frequencies of the audio signals. The diaphragm 110 may comprise a relatively stiff plastic material. The diaphragm 110 may have a resonant frequency of approximately 90 Hz. Although the resonant frequency may be decreased by increasing the diameter of the diaphragm 110 or by reducing the thickness of the plastic material, it may be difficult or impractical to form a diaphragm 110 having a conventional design that exhibits a lower resonant frequency because the size of the diaphragm 110 would be too large, and/or the diaphragm 110 would be too thin and susceptible to damage.
Referring to FIG. 2, in additional previously known speaker systems, a speaker assembly 200 may include a metal suspension member 210 (instead of a plastic diaphragm) connected to a rim of a support structure 220. The suspension member 210 may be generally circular, and may have beams connecting a radially outer portion and a radially inner platform portion to which a magnet or electromagnetic coil may be attached. As described above, the suspension member 210 is displaced when the attached magnet or electromagnetic coil moves back and forth in a magnetic field in response to an audio signal. As a result, the suspension member 210 generates audible sound waves in the air proximate the speaker assembly 200 that correspond to the frequencies of the audio signals. As shown in FIG. 2, individual beams 212 extend in multiple directions and have corners where distinct transitions in direction are made.